1. Field of the Invention
The invention relates to a catheter device which is a miniaturised pump.
2. Related Art
Implantable blood pumps are used increasingly in the treatment of patients with serous heart conditions. Such blood pumps have so far been provided mainly for long-term use. However, blood pumps are also being developed which are designed for short-term support for the heart and may be inserted by minimally invasive means. Here the medical objectives are stress-relief for and recovery of the heart, or to provide bridging until a possible heart transplant. The range of application of such pumps depends on the one hand on the simplicity of inserting them into the body, and on the other hand on the feasible technical properties, in particular the reliable operating life of the available pump systems which may be obtained. Ideally it should be possible to insert such a blood pump for short-term treatment by percutaneous-intravascular means without any surgical intervention.
In cardiogenic shock, the ejection performance of the left ventricle is considerably reduced. The reduced coronary supply can lead to irreversible heart failure. Through the use of a temporary left-ventricular support system, the pump function of the left ventricle should be partly or largely taken over and the coronary supply improved. In heart operations such a system may be used for both left and right ventricles and may replace a heart-lung machine.
A percutaneous-intravascular system which has to date been of clinical importance is the intra-aortal balloon pump (IABP). The intra-aortal balloon pump or intra-aortal counter-pulsation is a mechanical system, also used to support the pumping performance of the heart in patients with cardiogenic shock. This involves a catheter with a cylindrical plastic balloon being pushed ahead via the groin into the thoracic aorta (aorta thoracalis), so that the balloon lies below the outlet of the left clavicular artery (arteria subclavia sinistra). There the balloon is blown is inflated rhythmically by an external pump with every heart action in diastole with 30-40 cm3 helium and deflated in systole. In this way the balloon pump improves the blood supply to the heart muscle and also that of all other organs. The obtainable haemodynamic improvement is however very limited since, on account of the construction principle of the IABP, no active blood delivery takes place. Through counter-pulsation only the aorta is closed below the left ventricle in the rhythm of the heartbeat, so that the blood still discharged by the heart is pressed back and redistributed, also in the coronaries. There is no increase in blood flow.
A known transfemoral implantable micro axial pump, “Hemopump™” of the company Medtronic Inc., USA, represents after experimental and preliminary clinical testing a promising concept for effecting adequate relief of systemic heart strain. The intake nozzle of the pump is placed in the left ventricle retrogressively via the aortic valve. The pump rotor is located at the end of a cannula in the upper aorta descendens and is driven by an external motor. The disadvantage of the system is that the transfemoral implantation, due to the large diameter of the rotor, is possible only through an operation involving a femoral arteriotomy and if necessary by a graft coupling.
WO 99/44651 discloses an axial pump which may be introduced via the blood vessel system of a patient. The axial pump has a flexible, compressible tube which forms the pump housing. In the tube is a radially compressible rotor. The drive shaft of the rotor runs through a catheter. Together with the tube and the rotor, the catheter may be drawn into a cover hose. The radial compressibility of the components makes it possible to realise a small puncture diameter suitable for percutaneous implantation by the Seldinger technique. Through the unfolding in the heart vessel system, a relatively large pump diameter of 10 to 14 mm may be provided. This reduces the rotor speed and therefore the mechanical stress on the components.
Described in U.S. Pat. No. 4,753,221 is a catheter with an integrated blood pump which has folding blades. The blood pump is an axial pump provided with a balloon at its end. The balloon can be pumped up to unfold the pump jacket and to close the flow path leading past the pump, so fixing the pump in the blood vessel. In a further embodiment it is provided that a cup-shaped end of the catheter is arranged in a tubular guide catheter which is then withdrawn so as to unfold the cup-shaped end.
DE 10 059 714 C1 discloses an intravascular pump. The pump has a drive section and a pump section which are so small in diameter that they can be pushed through a blood vessel. A flexible cannula adjoins the pump section. To reduce flow resistance, the cannula may be expanded to a diameter which exceeds that of the drive section and pump section respectively. So that the pump may be introduced into the body by the Seldinger technique involving punctures in the blood vessel, the cannula is constricted, in which state it has a smaller diameter. In the blood vessel it is expanded so as to offer less flow resistance to the blood to be pumped.
Described in JP 4126158 and EP 0 445 782 A1 respectively is an artificial heart for implantation in the body. The artificial heart has a pump section and a drive section for driving the pump section. The pump section is relatively small and serves to accommodate an axial flow pump in the form of a screw pump. Different types of screw pump are provided.
Described in EP 0 364 293 A2 is a catheter with integral blood pump. A flexible edge extends over a tubular section of the catheter and contacts the wall of the aorta, ensuring by this means that all the blood within the aorta flows through the pump. In addition the flexible, expandable edge provides clearance between the pump and the aortic valve.